Catheters with enhanced flexibility and associated devices, systems, and methods

ABSTRACT

A neuromodulation catheter includes an elongate shaft and a neuromodulation element. The shaft includes two or more first cut shapes and two or more second cut shapes along a helical path extending around a longitudinal axis of the shaft. The first cut shapes are configured to at least partially resist deformation in response to longitudinal compression and tension on the shaft and torsion on the shaft in a first circumferential direction. The second cut shapes are configured to at least partially resist deformation in response to longitudinal compression on the shaft and torsion on the shaft in both first and second opposite circumferential directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the following applications:

(a) U.S. Provisional Application No. 61/717,067, filed Oct. 22, 2012;

(b) U.S. Provisional Application No. 61/793,144, filed Mar. 15, 2013;and

(c) U.S. Provisional Application No. 61/800,195, filed Mar. 15, 2013.

The foregoing applications are incorporated herein by reference in theirentireties.

TECHNICAL FIELD

The present technology is related to catheters. In particular, at leastsome embodiments are related to neuromodulation catheters having one ormore cuts and/or other features that enhance flexibility, such as tofacilitate intravascular delivery via transradial or other suitablepercutaneous transluminal approaches.

BACKGROUND

The sympathetic nervous system (SNS) is a primarily involuntary bodilycontrol system typically associated with stress responses. Fibers of theSNS extend through tissue in almost every organ system of the human bodyand can affect characteristics such as pupil diameter, gut motility, andurinary output. Such regulation can have adaptive utility in maintaininghomeostasis or in preparing the body for rapid response to environmentalfactors. Chronic activation of the SNS, however, is a common maladaptiveresponse that can drive the progression of many disease states.Excessive activation of the renal SNS in particular has been identifiedexperimentally and in humans as a likely contributor to the complexpathophysiology of hypertension, states of volume overload (e.g., heartfailure), and progressive renal disease.

Sympathetic nerves of the kidneys terminate in the renal blood vessels,the juxtaglomerular apparatus, and the renal tubules, among otherstructures. Stimulation of the renal sympathetic nerves can cause, forexample, increased renin release, increased sodium reabsorption, andreduced renal blood flow. These and other neural-regulated components ofrenal function are considerably stimulated in disease statescharacterized by heightened sympathetic tone. For example, reduced renalblood flow and glomerular filtration rate as a result of renalsympathetic efferent stimulation is likely a cornerstone of the loss ofrenal function in cardio-renal syndrome, (i.e., renal dysfunction as aprogressive complication of chronic heart failure). Pharmacologicstrategies to thwart the consequences of renal sympathetic stimulationinclude centrally-acting sympatholytic drugs, beta blockers (e.g., toreduce renin release), angiotensin-converting enzyme inhibitors andreceptor blockers (e.g., to block the action of angiotensin II andaldosterone activation consequent to renin release), and diuretics(e.g., to counter the renal sympathetic mediated sodium and waterretention). These pharmacologic strategies, however, have significantlimitations including limited efficacy, compliance issues, side effects,and others.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present technology can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present technology. For ease of reference,throughout this disclosure identical reference numbers may be used toidentify identical or at least generally similar or analogous componentsor features.

FIG. 1 is a partially schematic perspective view illustrating atherapeutic system including a neuromodulation catheter configured inaccordance with an embodiment of the present technology.

FIG. 2 is an enlarged partially cut-away side view of a shaft of theneuromodulation catheter shown in FIG. 1 illustrating a hypotube of theshaft and a cut extending along a helical path having varying pitchalong the length of the shaft.

FIG. 3 is a two-dimensional representation of the helical path shown inFIG. 2 and a portion of the shaft shown in FIG. 1.

FIG. 4 is a two-dimensional representation of the cut shown in FIG. 2along a first portion of the helical path shown in FIG. 3.

FIG. 5 is a two-dimensional representation of the cut shown in FIG. 2along a second portion of the helical path shown in FIG. 3.

FIGS. 6-9B are two-dimensional representations of cuts along portions ofhelical paths configured in accordance with embodiments of the presenttechnology.

FIGS. 10-12 are perspective views of shaft segments having guide wireexit openings with different positions relative to cuts configured inaccordance with embodiments of the present technology.

FIGS. 13 and 14 are perspective views of shaft segments includinghelically wound elongate members configured in accordance withembodiments of the present technology.

FIGS. 15 and 16 are side profile views of helically wound elongatemembers having windings with different average helix angles configuredin accordance with embodiments of the present technology.

FIG. 17 is a side profile view of a helically wound elongate memberhaving windings with different average helix angles on either side of atransition region configured in accordance with an embodiment of thepresent technology.

DETAILED DESCRIPTION

Neuromodulation catheters configured in accordance with at least someembodiments of the present technology include elongate shafts having oneor more cuts and/or other features that enhance flexibility withoutunduly compromising desirable axial stiffness (e.g., pushability orother responsiveness to axial force) and/or desirable torsionalstiffness (e.g., torqueability or other responsiveness to torsionalforce). For example, a neuromodulation catheter configured in accordancewith a particular embodiment of the present technology is sufficientlyflexible in some respects to facilitate deployment via a relatively longand/or tortuous intravascular path without excessive resistance, whilestill being sufficiently stiff in other respects so as to allowintravascular navigation or other suitable manipulation via anextracorporeal handle. Desirable axial stiffness can include, forexample, the capability of the shaft to be advanced or withdrawn alongthe length of an intravascular path without significantly buckling orelongating. Desirable torsional stiffness can include, for example, thecapability of the shaft to distally transfer rotational motion (e.g.,from a handle at a proximal end portion of the shaft to aneuromodulation element operably connected to the shaft via a distal endportion of the shaft) with close correspondence (e.g., at least aboutone-to-one correspondence). In addition or alternatively, desirabletorsional stiffness can include the capability of the shaft to distallytransfer rotational motion without causing whipping and/or diametricaldeformation of the shaft. Desirable axial and torsional stiffnesstogether can facilitate predictable and controlled transmission of axialand torsional force from the proximal end portion of the shaft towardthe distal end portion of the shaft while a neuromodulation catheter isin use.

Metal hypodermic (needle) tubing, aka hypotubing, is commonlyincorporated into small-diameter shafts of medical catheters to utilizethe wire-like physical properties of such material along with theuseable lumen extending therethrough. However, solid-walled metal tubingalso has known limitations regarding flexibility and kink resistance,and various designs have utilized slits, slots or other openings in thetubing wall to achieve improvements in flexibility. Such modificationsto the wall structure have always brought about compromises in physicalproperties in tension, compression, and torsion. Thus, in at least someconventional neuromodulation catheters, imparting flexibility canrequire unduly sacrificing axial stiffness and/or torsional stiffness.For example, creating a continuous helical cut in a relatively rigidhypotube of a shaft tends to increase the flexibility of the shaft, but,in some instances, the resulting coils between turns of the cut may alsotend to separate to an undesirable degree in response to tension on theshaft and/or torsion on the shaft in at least one circumferentialdirection. In some cases, this separation can cause a permanent ortemporary change in the length of the shaft (e.g., undesirableelongation of the shaft), a permanent or temporary diametricaldeformation of the shaft (e.g., undesirable flattening of across-section of the shaft), and/or torsional whipping. Such shaftbehavior can interfere with intravascular navigation and/or have otherundesirable effects on neuromodulation procedures.

Due, at least in part, to enhanced flexibility in combination withdesirable axial and torsional stiffness, neuromodulation cathetersconfigured in accordance with at least some embodiments of the presenttechnology can be well-suited for intravascular delivery to treatmentlocations (e.g., treatment locations within or otherwise proximate to arenal artery of a human patient) via transradial approaches (e.g.,approaches that include the radial artery, the subclavian artery, andthe descending aorta). Transradial approaches are typically moretortuous and longer than femoral approaches and at least some othercommonly used approaches. Transradial approaches can be desirable foraccessing certain anatomy, but other types of approaches (e.g., femoralapproaches) may be desirable in particularly tortuous anatomy or vesselshaving relatively small diameters. In some instances, however, use oftransradial approaches can provide certain advantages over use offemoral approaches. In some cases, for example, use of transradialapproaches can be associated with increased patient comfort, decreasedbleeding, and/or faster sealing of the percutaneous puncture siterelative to use of femoral approaches.

In addition to or instead of facilitating intravascular delivery viatransradial approaches, neuromodulation catheters configured inaccordance with at least some embodiments of the present technology canbe well suited for intravascular delivery via one or more other suitableapproaches, such as other suitable approaches that are shorter or longerthan transradial approaches and other suitable approaches that are lesstortuous or more tortuous than transradial approaches. For example,neuromodulation catheters configured in accordance with at least someembodiments of the present technology can be well suited forintravascular delivery via brachial approaches and/or femoralapproaches. Even when used with approaches that are generally shorterand/or less tortuous than transradial approaches, the combination offlexibility and desirable axial and torsional stiffness associated withneuromodulation catheters configured in accordance with at least someembodiments of the present technology can be beneficial, such as toaccommodate anatomical differences between patients and/or to reducevessel trauma during delivery, among other potential benefits.

Specific details of several embodiments of the present technology aredescribed herein with reference to FIGS. 1-17. Although many of theembodiments are described herein with respect to devices, systems, andmethods for intravascular renal neuromodulation, other applications andother embodiments in addition to those described herein are within thescope of the present technology. For example, at least some embodimentsmay be useful for intraluminal neuromodulation, for extravascularneuromodulation, for non-renal neuromodulation, and/or for use intherapies other than neuromodulation. It should be noted that otherembodiments in addition to those disclosed herein are within the scopeof the present technology. For example, in still other embodiments, thetechnology described herein may be used in devices, systems and methodsfor stent delivery and balloon angioplasty. Further, embodiments of thepresent technology can have different configurations, components, and/orprocedures than those shown or described herein. Moreover, a person ofordinary skill in the art will understand that embodiments of thepresent technology can have configurations, components, and/orprocedures in addition to those shown or described herein and that theseand other embodiments can be without several of the configurations,components, and/or procedures shown or described herein withoutdeviating from the present technology.

As used herein, the terms “distal” and “proximal” define a position ordirection with respect to a clinician or a clinician's control device(e.g., a handle of a neuromodulation catheter). The terms, “distal” and“distally” refer to a position distant from or in a direction away froma clinician or a clinician's control device. The terms “proximal” and“proximally” refer to a position near or in a direction toward aclinician or a clinician's control device. The headings provided hereinare for convenience only and should not be construed as limiting thesubject matter disclosed.

Selected Examples of Neuromodulation Catheters and Related Devices

FIG. 1 is a partially schematic perspective view illustrating atherapeutic system 100 configured in accordance with an embodiment ofthe present technology. The system 100 can include a neuromodulationcatheter 102, a console 104, and a cable 106 extending therebetween. Theneuromodulation catheter 102 can include an elongate shaft 108 having aproximal end portion 108 a and a distal end portion 108 b. A handle 110of the neuromodulation catheter 102 can be operably connected to theshaft 108 via the proximal end portion 108 a, and a neuromodulationelement 112 of the neuromodulation catheter 102 can be operablyconnected to the shaft 108 via the distal end portion 108 b. The shaft108 can be configured to locate the neuromodulation element 112intravascularly at a treatment location within or otherwise proximate toa body lumen (e.g., a blood vessel, a duct, an airway, or anothernaturally occurring lumen within the human body), and theneuromodulation element 112 can be configured to provide or support aneuromodulation treatment at the treatment location. The shaft 108 andthe neuromodulation element 112 can be 2, 3, 4, 5, 6, or 7 French or oneor more other suitable sizes.

In some embodiments, intravascular delivery of the neuromodulationcatheter 102 includes percutaneously inserting a guide wire (not shown)into a body lumen of a patient and moving the shaft 108 and theneuromodulation element 112 along the guide wire until theneuromodulation element 112 reaches a suitable treatment location. Inother embodiments, the neuromodulation catheter 102 can be a steerableor non-steerable device configured for use without a guide wire. Instill other embodiments, the neuromodulation catheter 102 can beconfigured for delivery via a guide catheter or sheath (not shown).

The console 104 can be configured to control, monitor, supply, and/orotherwise support operation of the neuromodulation catheter 102.Alternatively, the neuromodulation catheter 102 can be self-contained orotherwise configured for operation without connection to the console104. When present, the console 104 can be configured to generate aselected form and/or magnitude of energy for delivery to tissue at thetreatment location via the neuromodulation element 112 (e.g., via one ormore energy delivery elements (not shown) of the neuromodulation element112). The console 104 can have different configurations depending on thetreatment modality of the neuromodulation catheter 102. When theneuromodulation catheter 102 is configured for electrode-based,heat-element-based, or transducer-based treatment, for example, theconsole 104 can include an energy generator (not shown) configured togenerate radio frequency (RF) energy (e.g., monopolar and/or bipolar RFenergy), pulsed energy, microwave energy, optical energy, ultrasoundenergy (e.g., intravascularly delivered ultrasound, extracorporealultrasound, and/or high-intensity focused ultrasound (HIFU)),cryotherapeutic energy, direct heat energy, chemicals (e.g., drugsand/or other agents), radiation (e.g., infrared, visible, and/or gammaradiation), and/or another suitable type of energy. When theneuromodulation catheter 102 is configured for cryotherapeutictreatment, for example, the console 104 can include a refrigerantreservoir (not shown) and can be configured to supply theneuromodulation catheter 102 with refrigerant. Similarly, when theneuromodulation catheter 102 is configured for chemical-based treatment(e.g., drug infusion), the console 104 can include a chemical reservoir(not shown) and can be configured to supply the neuromodulation catheter102 with one or more chemicals.

In some embodiments, the system 100 includes a control device 114 alongthe cable 106. The control device 114 can be configured to initiate,terminate, and/or adjust operation of one or more components of theneuromodulation catheter 102 directly and/or via the console 104. Inother embodiments, the control device 114 can be absent or have anothersuitable location (e.g., within the handle 110). The console 104 can beconfigured to execute an automated control algorithm 116 and/or toreceive control instructions from an operator. Furthermore, the console104 can be configured to provide feedback to an operator before, during,and/or after a treatment procedure via an evaluation/feedback algorithm118.

FIG. 2 is an enlarged partially cut-away side view of the shaft 108illustrating a hypotube 120 concentrically disposed within an outsidewall 121. The hypotube 120 can be configured to reinforce the shaft 108against collapsing from lateral compression. For example, the hypotube120 can be made of a relatively strong material (e.g., nitinol,stainless steel, or another suitable metal). The hypotube 120 may bedisposed within all or a portion of the shaft 108. In some embodiments,for example, the hypotube 120 may only be disposed at a distal sectionof the shaft 108, and a proximal section of the shaft 108 may have adifferent arrangement and/or configuration. Tubes made of relativelystrong materials tend to be relatively stiff (e.g., resistant tobending) when unmodified. To increase the flexibility of theneuromodulation catheter 102, the shaft 108 can include a cut 122extending at least partially through a wall thickness of the hypotube120, the outside wall 121, or another suitable portion of the shaft 108.For example, the shaft 108 can have a longitudinal axis 124 and the cut122 can follow a helical path 126 that extends about the longitudinalaxis 124 (e.g., a coiled, spiral, or other similar form having two ormore turns consistently or variably spaced along the longitudinal axis124). The cut 122 can be continuous or discontinuous along the helicalpath 126. Furthermore, the shaft 108 can be cut along more than onehelical path 126 (e.g., a double helix having two or more helical paths126 having the same “hand” or chirality and spaced apart along thelongitudinal axis 124). The cut 122 can be formed, for example, usinglaser etching, electrical discharge machining, chemical etching, orother suitable techniques.

FIG. 3 is a two-dimensional representation of the helical path 126. Inparticular, FIG. 3 is a representation of the helical path 126 and aportion of the shaft 108 with the x-axis in FIG. 3 corresponding to thelongitudinal axis 124 along at least a portion of the length of theshaft 108 and the y-axis in FIG. 3 corresponding to the circumference ofthe shaft 108. In other words, FIG. 3 illustrates the helical path 126as though at least a portion of the shaft 108 were aligned with thex-axis and rolled along the y-axis with the helical path 126 unwindingto a flat ribbon or making an imprinted image as the shaft 108 isrolled. The helical path 126 can include a first portion 126 a, a secondportion 126 b, and a third portion 126 c therebetween. The first portion126 a, the second portion 126 b, and the third portion 126 c can extendaround portions of the longitudinal axis 124 corresponding to a firstsegment 127 a, a second segment 127 b, and a third segment 127 c of theshaft 108, respectively. In some embodiments, the first segment 127 a isdistal to the second and third segments 127 b, 127 c, and the thirdsegment 127 c is between the first and second segments 127 a, 127 b. Inother embodiments, the first, second, and third segments 127 a-c can bereversed or have another suitable arrangement. The first, second, andthird segments 127 a-c can be directly adjacent to one another or spacedapart from one another along the longitudinal axis 124. Furthermore, thefirst segment 127 a can be directly adjacent to or spaced apart from adistalmost portion of the shaft 108 (e.g., a junction between the shaft108 and the neuromodulation element 112), and the second segment 127 bcan be directly adjacent to or spaced apart from a proximalmost portionof the shaft 108 (e.g., a junction between the shaft 108 and the handle110).

As shown in FIG. 3, the first, second, and third portions 126 a-126 c ofthe helical path 126 can have different slopes when transposedtwo-dimensionally. These slopes can correspond to the axial density(e.g., frequency or pitch angle) of turns, shapes, or other suitablefeatures of the cut 122 along the longitudinal axis 124. For example,the first portion 126 a of the helical path 126 can have a greater slopethan the second portion 126 b, and the third portion 126 c can be curvedwith a slope that gradually transitions between the slopes of the firstand second portions 126 a, 126 b. Accordingly, the cut 122 can have agreater axial density of turns, shapes, or other suitable features alonga portion of the longitudinal axis 124 corresponding to the firstsegment 127 a than along a portion of the longitudinal axis 124corresponding to the second segment 127 b. Similarly, the axial densityof turns, shapes, or other suitable features of the cut 122 along thelongitudinal axis 124 can increase gradually or in another suitablemanner along the third segment 127 c from the second segment 127 btoward the first segment 127 a. For example, gradually increasing orotherwise transitioning the axial density of turns, shapes, slope, type,size/dimension, or other suitable features of the cut 122 may reducefocused stress on the shaft 108, which can reduce or eliminate kinkingor other undesirable behavior of the shaft 108 when it bends.

By varying the axial density of turns, shapes, or other suitablefeatures of the cut 122, different segments of the shaft 108 can havedifferent levels of flexibility. For example, with reference to FIGS.1-3 together, a greater axial density of turns, shapes, or othersuitable features can correspond to greater flexibility than a lesseraxial density of turns, shapes, or other suitable features. In somecases, a distance along the longitudinal axis 124 between theneuromodulation element 112 and a cut segment of the shaft 108 (e.g.,the first, second, or third segment 127 a-c) can be selected such thatthe cut segment tends to be disposed in or near a particular anatomicallocation when the neuromodulation catheter 102 is in use. For example,the distance along the longitudinal axis 124 between the neuromodulationelement 112 and the cut segment can be selected such that the cutsegment tends to be at least proximate to a relatively sharply angled orotherwise relatively tortuous anatomic region of an approach (e.g., atransradial or other suitable approach) when the neuromodulation element112 is at a selected treatment location (e.g., a treatment locationwithin or otherwise proximate to a renal artery of a human patient). Therelatively sharply angled or otherwise relatively tortuous region, forexample, can be a region within or otherwise proximate to a subclavianartery (e.g., a portion of a subclavian artery adjacent to thedescending aorta), an ostium of a renal artery, or another suitableanatomical feature. The axial density of turns, shapes, or othersuitable features of the cut 122 along different segments of the shaft108 and the relative flexibilities of the different segments can beselected to facilitate transradial catheterization or deployment of theneuromodulation catheter 102 via another suitable approach. In someembodiments, an axial density of turns, shapes, or other suitablefeatures of the cut 122 along the longitudinal axis 124 varies along thelength of the shaft 108 (e.g., to tailor the shaft 108 to the tortuosityor other geometry of different portions of a transradial or othersuitable approach). In other embodiments, the axial density of turns,shapes, or other suitable features of the cut 122 along the longitudinalaxis 124 can be consistent along the length of the shaft 108 (e.g., toincrease the overall flexibility of the shaft 108).

FIG. 4 is a two-dimensional representation of the cut 122 along thefirst portion 126 a of the helical path 126. Such a two-dimensionalrepresentation is as if the shaft were rolled over a flat surface toleave an imprint of the cut shape therein. In some instances, these twodimensional representations can be used as input for an automatedmanufacturing process used to form cut shapes along a path in a tubularworkpiece. With reference to FIGS. 2-4 together, the shaft 108 caninclude two or more first cut shapes 128 and two or more second cutshapes 130 interspersed along the helical path 126, with the first andsecond cut shapes 128, 130 forming portions of the cut 122. The firstcut shapes 128 can be configured to at least partially interlock tothereby resist deformation in response to a set of three types of forceacting on the shaft 108, and the second cut shapes 130 can be configuredto at least partially interlock to thereby resist deformation inresponse to a different, complementary set of three types of forceacting on the shaft 108. The sets can be different combinations of (a)compression along the longitudinal axis 124, (b) tension along thelongitudinal axis 124, (c) torsion in a first circumferential directionperpendicular to the longitudinal axis 124, and (d) torsion in a second,opposite circumferential direction perpendicular to the longitudinalaxis 124. For example, the first cut shapes 128 can be configured to atleast partially resist deformation in response to compression on theshaft 108, tension on the shaft 108, and torsion on the shaft 108 in thefirst circumferential direction, and the second cut shapes 130 can beconfigured to at least partially resist deformation in response tocompression on the shaft 108, torsion on the shaft 108 in the firstcircumferential direction, and torsion on the shaft 108 in a secondcircumferential direction opposite to the first circumferentialdirection. The first cut shapes 128 can be less resistant to deformationin response to torsion on the shaft 108 in the second circumferentialdirection than the second cut shapes 130. Similarly, the second cutshapes 130 can be less resistant to deformation in response to tensionon the shaft 108 than the first cut shapes 128. Working together, thefirst and second cut shapes 128, 130 can provide the shaft 108 withsufficient resistance to deformation in response to all types of axialand torsional force that may act on the shaft 108 during use of theneuromodulation catheter 102.

In some embodiments, the first and second cut shapes 128, 130 aresinusoidal and have amplitudes with different (e.g., perpendicular)orientations relative to the longitudinal axis 124. In otherembodiments, the first and second cut shapes 128, 130 can have othersuitable forms. For example, as shown in FIG. 4, the first cut shapes128 can individually include a first peak 132 (e.g., a first finger) anda second peak 134 (e.g., a second finger) with a first interface 136therebetween. The first interface 136 can be perpendicular to thelongitudinal axis 124 (FIG. 2). The second cut shapes 130 canindividually include a third peak 138 (e.g., a third finger) and afourth peak 140 (e.g., a fourth finger) with a second interface 142therebetween. The second interface 142 can be parallel to thelongitudinal axis 124. Alternatively, the first and second interfaces136, 142 can have other suitable angles relative to the longitudinalaxis 124, such as other suitable angles in which an angle between thefirst interface 136 and the longitudinal axis 124 is greater than anangle between the second interface 142 and the longitudinal axis 124.The first and second cut shapes 128, 130 can be configured to at leastpartially resist deformation in response to forces perpendicular to thefirst and second interfaces 136, 142, respectively. For example, suchforces can cause the first and second peaks 132, 134 or the third andfourth peaks 138, 140 to at least partially interlock and therebyprevent or reduce widening of the cut 122.

FIG. 5 is a two-dimensional representation of the cut 122 along thesecond portion 126 b of the helical path 126. With reference to FIGS. 2,3 and 5 together, an average length of the first interfaces 136, anaverage length of the second interfaces 142, or both can be different atdifferent portions of the helical path 126. For example, the averagelength of the second interfaces 142 can be greater among the second cutshapes 130 along the second portion 126 b of the helical path 126 andthe second segment 127 b of the shaft 108 than among the second cutshapes 130 along the first portion 126 a of the helical path 126 and thefirst segment 127 a of the shaft 108. In some cases, the average lengthof the first interfaces 136, the second interfaces 142, or both areselected based on different axial densities of turns, shapes, or othersuitable features of the cut 122 at different segments of the shaft 108.For example, when the axial density is greater, the lengths of the firstand second interfaces 136, 142 can be more restricted than when theaxial density is lower (e.g., so as to avoid overlapping at adjacentturns).

FIGS. 6-9B are two-dimensional representations of cuts along portions ofhelical paths configured in accordance with further embodiments of thepresent technology. As shown in FIG. 6, for example, in some embodimentsa shaft 108 includes an uncut region 144 with the first and second cutshapes 128, 130 positioned along portions of a helical path on eitherside of the uncut region 144. For example, the uncut region 144 can beone of many uncut regions 144 interspersed among the first and secondcut shapes 128, 130 along the helical path. In other embodiments, thefirst and second cut shapes 128, 130 can be portions of a continuouscut. For example, as shown in FIG. 7, the first and second cut shapes128, 130 can be in suitable patterns along the helical path other thanone-to-one alternating patterns. Suitable patterns can include, forexample, random patterns, non-random patterns, two-to-one alternatingpatterns, two-to-two alternating patterns, and three-to-two alternatingpatterns, among others. Furthermore, the spacing between adjacent firstand second cut shapes 128, 130 can be consistent or variable.

Referring next to FIG. 8, a shaft can include two or more third cutshapes 146 and two or more fourth cut shapes 148 interspersed along ahelical path. The individual third cut shapes 146 can be configured tofully interlock rather than partially interlock. For example, theindividual third cut shapes 146 can be configured to at least partiallyresist deformation in response to compression on the shaft, tension onthe shaft, torsion on the shaft in the first circumferential direction,and torsion on the shaft in the second circumferential direction. Theshaft, for example, can include tabs 149 (e.g., protrusions, lobes, orother suitable structures) adjacent to the third cut shapes 146, withthe third cut shapes 146 forming recesses complementary to the tabs 149.The individual tabs 149 can include a flared portion 149 a (e.g., arounded head portion) and a restricted portion 149 b (e.g., a roundedneck portion), or other suitable structures. The fourth cut shapes 148can be sinusoidal and have amplitudes oriented perpendicularly to thehelical path. For example, the individual fourth cut shapes 148 caninclude a first peak 150 and a second peak 152 with an interface 154therebetween that is diagonal relative to a longitudinal axis of theshaft and perpendicular to the helical path.

As shown in FIGS. 9A and 9B, in some embodiments a shaft includes thethird cut shapes 146 without the fourth cut shapes 148. Referring toFIG. 9B, for example, the shaft includes tabs 302 adjacent to respectivethird cut shapes 300. The individual tabs 302 and corresponding thirdcut shapes 300, for example, can comprise a wedge-shaped arrangementwith the tabs 302 including a wedge-shaped portion 304 (i.e., a “tail”)and a restricted neck portion 306, while the complementary third cutshapes 300 form recesses or sockets (i.e., “tail sockets”) complementaryto the tabs 302. In some embodiments, the tabs 302 and third cut shapes300 may fit snugly with very little room between the respective portionsof the two components. In other embodiments, however, there may be somespace between at least a portion of each wedge-shaped portion 304 andthe complementary socket portion to allow some amount of relativemovement between the components.

In other embodiments, the shaft can include the fourth cut shapes 148without the third cut shapes 146. Although the third and fourth cutshapes 146, 148 are potentially useful alone or in combination withother cut shapes, it is expected that combinations of the first andsecond cut shapes 128, 130 may be more stable than the third and fourthcut shapes 146, 148 alone or in combination during use of aneuromodulation catheter. For example, is it expected that combinationsof cut shapes that impart resistance to complementary sets of fewer thanall types of axial and torsional force that may act on a shaft duringuse of a neuromodulation catheter may facilitate dissipation oflocalized stresses along a cut. It will further be appreciated thatcatheters configured in accordance with embodiments of the presenttechnology can include various combinations of cut shapes tailored toprovide a desired level of flexibility and/or control for differentapplications.

FIGS. 10-12 are perspective views of shaft segments having guide wireexit openings with different positions relative to cuts. For example,with reference to FIGS. 5 and 10, in some embodiments a shaft segment156 having the first and second cut shapes 128, 130 has a guide wireexit opening 158 in place of a third peak 138 of one of the second cutshapes 130. In other embodiments, the guide wire exit opening 158 can bein place of the first peak 132, the second peak 134, the fourth peak140, or a combination thereof including or not including the third peak138. As another example, with reference to FIGS. 5 and 11, a shaftsegment 160 having the first and second cut shapes 128, 130 can have aguide wire exit opening 162 between (e.g., about evenly between)adjacent turns of a helical path along which the first and second cutshapes 128, 130 are distributed. As yet another example, with referenceto FIGS. 5, 6 and 12, a shaft segment 164 having the first and secondcut shapes 128, 130 and the uncut region 146 (e.g., as described abovewith reference to FIG. 6) can have a guide wire exit opening 166 at theuncut region 146. In other examples, the guide wire exit openings mayhave other suitable positions relative to the cuts. Furthermore,although the guide wire exit openings 158, 162, 166 are illustrated inFIGS. 10-12 as generally oval with their longitudinal axes aligned withlongitudinal axes of the corresponding shaft segments 156, 160, 164, theguide wire exit openings 158, 162, 166 can have other suitable shapesand/or orientations.

Instead of or in addition to a cut tube, neuromodulation cathetersconfigured in accordance with at least some embodiments of the presenttechnology can include one or more elongate members (e.g., filaments,wires, ribbons, or other suitable structures) helically wound into oneor more tubular shapes. Similar to the axial density of turns, shapes,or other suitable features of a cut along a longitudinal axis of a shaft(e.g., as discussed above with reference to FIG. 3), the axial densityof windings of a helically wound elongate member along a longitudinalaxis of a shaft can be selected to change the flexibility of the shaft.For example, an axial density of windings along a longitudinal axis of ashaft can be selected to facilitate intravascular delivery of aneuromodulation element to a treatment location within or otherwiseproximate to a renal artery of a human patient via a transradial orother suitable approach. In some embodiments, an axial density ofwindings along a longitudinal axis of a shaft varies along the length ofthe shaft (e.g., to tailor the shaft to the tortuosity or other geometryof different portions of a transradial or other suitable approach). Inother embodiments, the axial density of windings along a longitudinalaxis of a shaft can be consistent along the length of the shaft (e.g.,to increase the overall flexibility of the shaft).

FIGS. 13 and 14 are perspective views of shaft segments includinghelically wound elongate members configured in accordance withembodiments of the present technology. With reference to FIG. 13, ashaft 168 can include a first helically wound elongate member 170 havinga series of first windings 172 at least partially forming a firsttubular structure 174. The shaft 168 can further include a secondhelically wound elongate member 176 having a series of second windings178 at least partially forming a second tubular structure 180. The firsttubular structure 174 can be disposed within the second tubularstructure 180, and the first and second tubular structures 174, 180 canbe concentric.

In some embodiments, at least one of the first and second helicallywound elongate members 170, 176 is multifilar. For example, in theembodiment shown in FIG. 13, the second helically wound elongate member176 is multifilar with five parallel filaments (individually identifiedin FIG. 13 as 176 a-e), and the first helically wound elongate member170 is monofilar. In other embodiments, the second helically woundelongate member 176 can be monofilar and the first helically woundelongate member 170 can be multifilar. In still other embodiments, boththe first and second helically wound elongate members 170, 176 can bemonofilar or multifilar. Furthermore, in some embodiments, the firstwindings 172, the second windings 178, or both are “openly wound” orspaced apart along a longitudinal axis of the shaft 168. For example, inthe embodiment shown in FIG. 13, the second windings 178 are shownspaced apart along the longitudinal axis of the shaft 168 with gaps 181between adjacent second windings 178, and the first windings 172 areshown not spaced apart along the longitudinal axis of the shaft 168. Inother embodiments, the second windings 178 can be not spaced apart alongthe longitudinal axis of the shaft 168 and the first windings 172 can bespaced apart along the longitudinal axis of the shaft 168. In stillother embodiments, both the first and second windings 172, 178 can bespaced apart or not spaced apart along the longitudinal axis of theshaft 168.

With reference to FIG. 14, a shaft 182 can include a third helicallywound elongate member 183 having a series of third windings 184 at leastpartially forming a third tubular structure 186. The first and secondtubular structures 174, 180 can be disposed within the third tubularstructure 186, and the first, second, and third tubular structures 174,180, 186 can be concentric. In the embodiment shown in FIG. 14, thethird helically wound elongate member 183 is multifilar with parallelfilaments (individually identified in FIG. 14 as 183 a-e). In otherembodiments, the third helically wound elongate member 183 can bemonofilar. Furthermore, in embodiments having more than one helicallywound layer, the layers may be counter-wound, e.g. a right-hand helicallayer may surround a left-hand helical layer. The shaft 182 can furtherinclude biocompatible jacket 188 at least partially encasing the first,second, and third tubular structures 174, 180, 186. The biocompatiblejacket 188, for example, can be at least partially made of a smoothpolymer or other suitable material well suited for sliding contact withan inner wall of a body lumen.

FIG. 15 is a side profile view of a helically wound elongate member 190having a series of windings 192 with an average helix angle A1. FIG. 16is a side profile view of a helically wound elongate member 194 having aseries of windings 196 with an average helix angle A2. With reference toFIGS. 14-16 together, the first windings 172, the second windings 178,the third windings 184, or a subset thereof, can have different averagehelix angles. For example, a first average helix angle of the firstwindings 172 can be different than a second average helix angle of thesecond windings 178 by an angle within a range from about 10 degrees toabout 140 degrees (e.g., a range from about 30 degrees to about 120degrees, or another suitable range). Similarly, the first average helixangle of the first windings 172 can be different than a third averagehelix angle of the third windings 184 by an angle within a range fromabout 10 degrees to about 140 degrees (e.g., a range from about 30degrees to about 120 degrees, or another suitable range) and the secondaverage helix angle of the second windings 178 can be between (e.g.,about midway between) the first and third average helix angles of thefirst and third windings 172, 184, respectively.

FIG. 17 is a side profile view of a helically wound elongate member 198having a series of windings 200 with different average helix angles andopposite chirality on either side of a transition region 202. Althoughan abrupt change in average helix angle at the transition region 202 isshown in FIG. 17, the change at the transition region 202 canalternatively be gradual or incremental. With reference to FIGS. 14, 15and 17 together, in some embodiments the first windings 172, the secondwindings 178, and/or the third windings 184 include one or moretransition regions 202. In other embodiments, the first windings 172,the second windings 178, and the third windings 184 can have consistenthelix angles along the length of the shaft 168. Including one or moretransition regions 202 can be useful, for example, to allow a differencebetween average helix angles of windings within concentric tubularstructures to vary (e.g., to change at least once) along the length ofthe shaft 168. For example, this difference can decrease (e.g.,abruptly, gradually, or incrementally) distally along the length of theshaft 168. It is expected that increasing a difference between averagehelix angles of windings within concentric tubular structures may reduceflexibility and increase axial and torsional stiffness of a shaft, andthat decreasing a difference between average helix angles of windingswithin concentric tubular structures may increase flexibility anddecrease axial and torsional stiffness of a shaft. Accordingly, thepositions of the transition regions 202 can be selected to change theflexibility of the shaft relative to the axial and torsional stiffnessof the shaft along the length of a shaft (e.g., to facilitateintravascular delivery of a neuromodulation element to a treatmentlocation within or otherwise proximate to a renal artery of a humanpatient via a transradial or other suitable approach).

Instead of or in addition to a cut tube and/or a helically woundelongate member, neuromodulation catheters configured in accordance withat least some embodiments of the present technology can include shaftshaving one or more segments with different shape memory properties. Withreference to FIG. 3, for example, the first segment 127 a can be made atleast partially of a first shape-memory alloy, the second segment 127 bcan be made at least partially of a second shape-memory alloy, and thethird segment 127 c can be made at least partially of a thirdshape-memory alloy. The first, second, and third shape-memory alloys canbe different or the same. In some embodiments, the first, second, andthird shape-memory alloys are nitinol. In other embodiments, the first,second, and third shape-memory alloys can be other suitable materials.The first, second, and third shape-memory alloys can have first, second,and third shape-memory transformation temperature ranges, respectively.For example, when the first, second, and third shape-memory alloys arenitinol, the first, second, and third shape-memory transformationtemperature ranges can include Af temperatures.

The second shape-memory transformation temperature range and/or an Aftemperature of the second shape-memory transformation temperature rangecan be lower than the first shape-memory transformation temperaturerange and/or an Af temperature of the first shape-memory transformationtemperature range. For example, the first shape-memory transformationtemperature range can include an Af temperature greater than bodytemperature and the second shape-memory transformation temperature rangeincludes an Af temperature less than body temperature. A shape-memorytransformation temperature range and/or an Af temperature of ashape-memory transformation temperature range of the shaft 108 canincrease (e.g., abruptly, gradually, or incrementally) along the thirdsegment 127 c from the second segment 127 b toward the first segment 127a. In some embodiments, to vary the shape-memory transformationtemperature ranges and/or Af temperatures along the length of the shaft108, the first, second, and third segments 127 a-c are formed separatelyand then joined. In other embodiments, the shape-memory transformationtemperature ranges and/or the Af temperatures along the length of theshaft 108 can be achieved by processing the first, second, and thirdsegments 127 a-c differently while they are joined. For example, one ofthe first, second, and third segments 127 a-c can be subjected to a heattreatment to change its shape-memory transformation temperature rangeand/or Af temperature while the others of the first, second, and thirdsegments 127 a-c are thermally insulated.

It is expected that greater shape-memory transformation temperatureranges and/or Af temperatures of shape-memory transformation temperatureranges may increase flexibility and decrease axial and torsionalstiffness of a shaft (e.g., by causing nitinol to tend to assume aaustenite phase at body temperature), and that lower shape-memorytransformation temperature ranges and/or Af temperatures of shape-memorytransformation temperature ranges may decrease flexibility and increaseaxial and torsional stiffness of a shaft (e.g., by causing nitinol totend to assume a martensite phase at body temperature). Accordingly, thepositions of segments of a shaft having different shape-memorytransformation temperature ranges and/or Af temperatures of shape-memorytransformation temperature ranges can be selected to change theflexibility of the shaft relative to the axial and torsional stiffnessof the shaft along the length of a shaft (e.g., to facilitateintravascular delivery of a neuromodulation element to a treatmentlocation within or otherwise proximate to a renal artery of a humanpatient via a transradial or other suitable approach).

Renal Neuromodulation

Renal neuromodulation is the partial or complete incapacitation or othereffective disruption of nerves of the kidneys (e.g., nerves terminatingin the kidneys or in structures closely associated with the kidneys). Inparticular, renal neuromodulation can include inhibiting, reducing,and/or blocking neural communication along neural fibers (e.g., efferentand/or afferent neural fibers) of the kidneys. Such incapacitation canbe long-term (e.g., permanent or for periods of months, years, ordecades) or short-term (e.g., for periods of minutes, hours, days, orweeks). Renal neuromodulation is expected to contribute to the systemicreduction of sympathetic tone or drive and/or to benefit at least somespecific organs and/or other bodily structures innervated by sympatheticnerves. Accordingly, renal neuromodulation is expected to be useful intreating clinical conditions associated with systemic sympatheticoveractivity or hyperactivity, particularly conditions associated withcentral sympathetic overstimulation. For example, renal neuromodulationis expected to efficaciously treat hypertension, heart failure, acutemyocardial infarction, metabolic syndrome, insulin resistance, diabetes,left ventricular hypertrophy, chronic and end stage renal disease,inappropriate fluid retention in heart failure, cardio-renal syndrome,polycystic kidney disease, polycystic ovary syndrome, osteoporosis,erectile dysfunction, and sudden death, among other conditions.

Renal neuromodulation can be electrically-induced, thermally-induced,chemically-induced, or induced in another suitable manner or combinationof manners at one or more suitable treatment locations during atreatment procedure. The treatment location can be within or otherwiseproximate to a renal lumen (e.g., a renal artery, a ureter, a renalpelvis, a major renal calyx, a minor renal calyx, or another suitablestructure), and the treated tissue can include tissue at least proximateto a wall of the renal lumen. For example, with regard to a renalartery, a treatment procedure can include modulating nerves in the renalplexus, which lay intimately within or adjacent to the adventitia of therenal artery.

Renal neuromodulation can include a cryotherapeutic treatment modalityalone or in combination with another treatment modality. Cryotherapeutictreatment can include cooling tissue at a treatment location in a mannerthat modulates neural function. For example, sufficiently cooling atleast a portion of a sympathetic renal nerve can slow or potentiallyblock conduction of neural signals to produce a prolonged or permanentreduction in renal sympathetic activity. This effect can occur as aresult of cryotherapeutic tissue damage, which can include, for example,direct cell injury (e.g., necrosis), vascular or luminal injury (e.g.,starving cells from nutrients by damaging supplying blood vessels),and/or sublethal hypothermia with subsequent apoptosis. Exposure tocryotherapeutic cooling can cause acute cell death (e.g., immediatelyafter exposure) and/or delayed cell death (e.g., during tissue thawingand subsequent hyperperfusion). Neuromodulation using a cryotherapeutictreatment in accordance with embodiments of the present technology caninclude cooling a structure proximate an inner surface of a body lumenwall such that tissue is effectively cooled to a depth where sympatheticrenal nerves reside. For example, in some embodiments, a coolingassembly of a cryotherapeutic device can be cooled to the extent that itcauses therapeutically-effective, cryogenic renal neuromodulation. Inother embodiments, a cryotherapeutic treatment modality can includecooling that is not configured to cause neuromodulation. For example,the cooling can be at or above cryogenic temperatures and can be used tocontrol neuromodulation via another treatment modality (e.g., to protecttissue from neuromodulating energy).

Renal neuromodulation can include an electrode-based or transducer-basedtreatment modality alone or in combination with another treatmentmodality. Electrode-based or transducer-based treatment can includedelivering electricity and/or another form of energy to tissue at atreatment location to stimulate and/or heat the tissue in a manner thatmodulates neural function. For example, sufficiently stimulating and/orheating at least a portion of a sympathetic renal nerve can slow orpotentially block conduction of neural signals to produce a prolonged orpermanent reduction in renal sympathetic activity. A variety of suitabletypes of energy can be used to stimulate and/or heat tissue at atreatment location. For example, neuromodulation in accordance withembodiments of the present technology can include delivering RF energy,pulsed energy, microwave energy, optical energy, focused ultrasoundenergy (e.g., high-intensity focused ultrasound energy), or anothersuitable type of energy alone or in combination. An electrode ortransducer used to deliver this energy can be used alone or with otherelectrodes or transducers in a multi-electrode or multi-transducerarray. Furthermore, the energy can be applied from within the body(e.g., within the vasculature or other body lumens in a catheter-basedapproach) and/or from outside the body (e.g., via an applicatorpositioned outside the body). Furthermore, energy can be used to reducedamage to non-targeted tissue when targeted tissue adjacent to thenon-targeted tissue is subjected to neuromodulating cooling.

Neuromodulation using focused ultrasound energy (e.g., high-intensityfocused ultrasound energy) can be beneficial relative to neuromodulationusing other treatment modalities. Focused ultrasound is an example of atransducer-based treatment modality that can be delivered from outsidethe body. Focused ultrasound treatment can be performed in closeassociation with imaging (e.g., magnetic resonance, computed tomography,fluoroscopy, ultrasound (e.g., intravascular or intraluminal), opticalcoherence tomography, or another suitable imaging modality). Forexample, imaging can be used to identify an anatomical position of atreatment location (e.g., as a set of coordinates relative to areference point). The coordinates can then entered into a focusedultrasound device configured to change the power, angle, phase, or othersuitable parameters to generate an ultrasound focal zone at the locationcorresponding to the coordinates. The focal zone can be small enough tolocalize therapeutically-effective heating at the treatment locationwhile partially or fully avoiding potentially harmful disruption ofnearby structures. To generate the focal zone, the ultrasound device canbe configured to pass ultrasound energy through a lens, and/or theultrasound energy can be generated by a curved transducer or by multipletransducers in a phased array (curved or straight).

Heating effects of electrode-based or transducer-based treatment caninclude ablation and/or non-ablative alteration or damage (e.g., viasustained heating and/or resistive heating). For example, a treatmentprocedure can include raising the temperature of target neural fibers toa target temperature above a first threshold to achieve non-ablativealteration, or above a second, higher threshold to achieve ablation. Thetarget temperature can be higher than about body temperature (e.g.,about 37° C.) but less than about 45° C. for non-ablative alteration,and the target temperature can be higher than about 45° C. for ablation.Heating tissue to a temperature between about body temperature and about45° C. can induce non-ablative alteration, for example, via moderateheating of target neural fibers or of vascular or luminal structuresthat perfuse the target neural fibers. In cases where vascularstructures are affected, the target neural fibers can be deniedperfusion resulting in necrosis of the neural tissue. Heating tissue toa target temperature higher than about 45° C. (e.g., higher than about60° C.) can induce ablation, for example, via substantial heating oftarget neural fibers or of vascular or luminal structures that perfusethe target fibers. In some patients, it can be desirable to heat tissueto temperatures that are sufficient to ablate the target neural fibersor the vascular or luminal structures, but that are less than about 90°C. (e.g., less than about 85° C., less than about 80° C., or less thanabout 75° C.).

Renal neuromodulation can include a chemical-based treatment modalityalone or in combination with another treatment modality. Neuromodulationusing chemical-based treatment can include delivering one or morechemicals (e.g., drugs or other agents) to tissue at a treatmentlocation in a manner that modulates neural function. The chemical, forexample, can be selected to affect the treatment location generally orto selectively affect some structures at the treatment location overother structures. The chemical, for example, can be guanethidine,ethanol, phenol, a neurotoxin, or another suitable agent selected toalter, damage, or disrupt nerves. A variety of suitable techniques canbe used to deliver chemicals to tissue at a treatment location. Forexample, chemicals can be delivered via one or more needles originatingoutside the body or within the vasculature or other body lumens. In anintravascular example, a catheter can be used to intravascularlyposition a therapeutic element including a plurality of needles (e.g.,micro-needles) that can be retracted or otherwise blocked prior todeployment. In other embodiments, a chemical can be introduced intotissue at a treatment location via simple diffusion through a body lumenwall, electrophoresis, or another suitable mechanism. Similar techniquescan be used to introduce chemicals that are not configured to causeneuromodulation, but rather to facilitate neuromodulation via anothertreatment modality.

Returning to FIG. 1, in another embodiment the system 100 may comprise astent delivery system. In this embodiment, stent delivery catheter 102includes stent delivery element 112. In one embodiment, stent deliveryelement 112 includes a dilatation balloon with a balloon expandablestent disposed thereon. The stent delivery catheter 102 also includeshandle 110 operably connected to shaft 108 via proximal end portion 108a. The shaft 108 can be configured to locate the stent delivery element112 intravascularly at a treatment location within or otherwiseproximate to a body lumen (e.g., coronary artery). The handle 110 isconfigured to aid in the delivery and deployment of the stent (notshown) to the treatment location. The stent delivery system 100 does notinclude the console 104 or cable 106.

The stent of stent delivery element 112 may be any balloon expandablestent as known to one of ordinary skill in the art. In one embodiment,for example, the stent is formed from a single wire forming a continuoussinusoid. The stent may include a coating disposed on the surface of thestent. The coating may include a polymer and/or a therapeutic agent. Inone embodiment, the coating includes a Biolinx™ polymer blended with alimus drug. In another embodiment, the stent is a drug filled stenthaving a lumen filled with a therapeutic agent. In still anotherembodiment, element 112 does not include a stent disposed on thedilatation balloon.

CONCLUSION

This disclosure is not intended to be exhaustive or to limit the presenttechnology to the precise forms disclosed herein. Although specificembodiments are disclosed herein for illustrative purposes, variousequivalent modifications are possible without deviating from the presenttechnology, as those of ordinary skill in the relevant art willrecognize. In some cases, well-known structures and functions have notbeen shown and/or described in detail to avoid unnecessarily obscuringthe description of the embodiments of the present technology. Althoughsteps of methods may be presented herein in a particular order, inalternative embodiments the steps may have another suitable order.Similarly, certain aspects of the present technology disclosed in thecontext of particular embodiments can be combined or eliminated in otherembodiments. Furthermore, while advantages associated with certainembodiments may have been disclosed in the context of those embodiments,other embodiments can also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages or other advantagesdisclosed herein to fall within the scope of the present technology.Accordingly, this disclosure and associated technology can encompassother embodiments not expressly shown and/or described herein.

Throughout this disclosure, the singular terms “a,” “an,” and “the”include plural referents unless the context clearly indicates otherwise.Similarly, unless the word “or” is expressly limited to mean only asingle item exclusive from the other items in reference to a list of twoor more items, then the use of “or” in such a list is to be interpretedas including (a) any single item in the list, (b) all of the items inthe list, or (c) any combination of the items in the list. Additionally,the terms “comprising” and the like are used throughout this disclosureto mean including at least the recited feature(s) such that any greaternumber of the same feature(s) and/or one or more additional types offeatures are not precluded. Directional terms, such as “upper,” “lower,”“front,” “back,” “vertical,” and “horizontal,” may be used herein toexpress and clarify the relationship between various elements. It shouldbe understood that such terms do not denote absolute orientation.Reference herein to “one embodiment,” “an embodiment,” or similarformulations means that a particular feature, structure, operation, orcharacteristic described in connection with the embodiment can beincluded in at least one embodiment of the present technology. Thus, theappearances of such phrases or formulations herein are not necessarilyall referring to the same embodiment. Furthermore, various particularfeatures, structures, operations, or characteristics may be combined inany suitable manner in one or more embodiments.

1-39. (canceled)
 40. A method, comprising: transluminally positioning anenergy delivery element of a catheter within a renal blood vessel of ahuman patient, wherein the catheter is advanced along a transradialapproach to the renal blood vessel of the patient, and wherein theenergy delivery element is at distal end region of a shaft of thecatheter, the shaft including— a first hypotube segment concentricallydisposed within the shaft, wherein the first hypotube segment iscomposed, at least in part, of a first shape-memory alloy having a firstshape-memory transformation temperature range, and a second hypotubesegment concentrically disposed within the shaft proximal to the firsthypotube segment along a longitudinal axis of the shaft, wherein thesecond hypotube segment is composed, at least in part, of a secondshape-memory alloy having a second shape-memory transformationtemperature range lower than the first shape-memory transformationtemperature range; and delivering energy via the energy delivery elementto at least partially ablate one or more renal nerves innervating akidney of the patient.
 41. The method of claim 40, further comprisingwithdrawing the catheter from the patient along the transradial approachafter delivering energy via the energy delivery element to conclude theprocedure.
 42. The method of claim 40 wherein: the first shape-memoryalloy is nitinol; and the method further comprises causing the nitinolof the first hypotube segment to assume an austenite phase whiletransluminally positioning the energy delivery element.
 43. The methodof claim 40 wherein: the second shape-memory alloy is nitinol; and themethod further comprises causing the nitinol of the second hypotubesegment to assume a martensite phase while transluminally positioningthe energy delivery element.
 44. The method of claim 40 wherein thefirst and second shape-memory alloys are nitinol.
 45. The method ofclaim 40 wherein: the first shape-memory transformation temperaturerange includes an Af temperature greater than body temperature; and thesecond shape-memory transformation temperature range includes an Aftemperature less than body temperature.
 46. The method of claim 40,further comprising distally transferring rotational motion from a handleat a proximal region of the catheter and external to the patient and tothe energy delivery element via the shaft.
 47. The method of claim 40wherein delivering energy via the energy delivery element comprisesdelivering radio frequency (RF) energy via the energy delivery element.48. The method of claim 40 wherein delivering energy via the energydelivery element comprises delivering electrical energy via the energydelivery element.
 49. The method of claim 40 wherein the first andsecond shape-memory alloys are the same.
 50. The method of claim 40wherein: the shaft further comprises a third segment made at leastpartially of a third shape-memory alloy, the third segment being betweenthe first and second segments along the longitudinal axis; the first,second, and third shape-memory alloys are the same; and a shape-memorytransformation temperature range of the third shape-memory alloygradually increases along the third segment from the second segmenttoward the first segment.
 51. The method of claim 40, further comprisinglocating the first and second hypotube segments at a sharply angledportion of the transradial approach when the energy delivery element ispositioned within the renal blood vessel.
 52. The method of claim 40wherein transluminally positioning an energy delivery element of acatheter within a renal blood vessel comprises advancing the catheterover a guidewire along the transradial approach.